用C++写定义一个动态数组类用于存放学生信息（学号、姓名、高数成绩、英语成绩），实现学生成绩的管理。实现如下功能：程序运行后，提示使用者输入学生的个数，根据学生的个数动态的创建数组。然后逐个输入每个学生的学号、高数成绩、英语成绩。录入时，已经录入的学号不允许再次录入。成绩范围在0-100分，如超出，则为无效。完成录入后，将成绩以列表的形式输出，统计并打印出每门课程的最高成绩、最低成绩、平均成绩。之后提示可进行成绩查询，输入学号，如果学号正确，输出该学生的成绩。如果学号不正确，提示重新输入。成绩列表示例学号 姓名 高数成绩 英语成绩 ---------------------------------------------------- 20140823 张三 98 87 20140824 李四 78 99 … ----------------------------------------------------

好的，我来帮您解答这个问题。以下是动态数组类的实现代码：

#include <iostream>
#include <string>
#include <vector>

using namespace std;

class Student {
public:
    string id;
    string name;
    int mathScore;
    int engScore;
};

class StudentManager {
public:
    void createStudents() {
        int num;
        cout << "请输入学生人数：";
        cin >> num;
        students.resize(num);
        for (int i = 0; i < num; i++) {
            string id;
            cout << "请输入学生学号：";
            cin >> id;
            for (int j = 0; j < i; j++) {
                if (students[j].id == id) {
                    cout << "学号已存在，请重新输入：" << endl;
                    cin >> id;
                    j = -1;
                }
            }
            students[i].id = id;
            cout << "请输入学生姓名：";
            cin >> students[i].name;
            cout << "请输入学生高数成绩：";
            cin >> students[i].mathScore;
            if (students[i].mathScore < 0 || students[i].mathScore > 100) {
                students[i].mathScore = -1;
            }
            cout << "请输入学生英语成绩：";
            cin >> students[i].engScore;
            if (students[i].engScore < 0 || students[i].engScore > 100) {
                students[i].engScore = -1;
            }
        }
    }

    void showStudents() {
        cout << "学号\t姓名\t高数成绩\t英语成绩" << endl;
        cout << "---------------------------------------" << endl;
        for (int i = 0; i < students.size(); i++) {
            cout << students[i].id << "\t" << students[i].name << "\t";
            if (students[i].mathScore == -1) {
                cout << "无效\t";
            } else {
                cout << students[i].mathScore << "\t";
            }
            if (students[i].engScore == -1) {
                cout << "无效\t";
            } else {
                cout << students[i].engScore << "\t";
            }
            cout << endl;
        }
        cout << "---------------------------------------" << endl;
    }

    void showStatistics() {
        int mathSum = 0, engSum = 0, mathMax = 0, engMax = 0, mathMin = 100, engMin = 100;
        double mathAvg = 0, engAvg = 0;
        int num = students.size();
        for (int i = 0; i < num; i++) {
            if (students[i].mathScore != -1) {
                mathSum += students[i].mathScore;
                if (students[i].mathScore > mathMax) {
                    mathMax = students[i].mathScore;
                }
                if (students[i].mathScore < mathMin) {
                    mathMin = students[i].mathScore;
                }
            }
            if (students[i].engScore != -1) {
                engSum += students[i].engScore;
                if (students[i].engScore > engMax) {
                    engMax = students[i].engScore;
                }
                if (students[i].engScore < engMin) {
                    engMin = students[i].engScore;
                }
            }
        }
        mathAvg = mathSum * 1.0 / (num * 1.0);
        engAvg = engSum * 1.0 / (num * 1.0);
        cout << "高数成绩：最高分：" << mathMax << "，最低分：" << mathMin << "，平均分：" << mathAvg << endl;
        cout << "英语成绩：最高分：" << engMax << "，最低分：" << engMin << "，平均分：" << engAvg << endl;
    }

    void searchStudent() {
        string id;
        cout << "请输入要查询的学生学号：";
        cin >> id;
        for (int i = 0; i < students.size(); i++) {
            if (students[i].id == id) {
                cout << "学号\t姓名\t高数成绩\t英语成绩" << endl;
                cout << "---------------------------------------" << endl;
                cout << students[i].id << "\t" << students[i].name << "\t";
                if (students[i].mathScore == -1) {
                    cout << "无效\t";
                } else {
                    cout << students[i].mathScore << "\t";
                }
                if (students[i].engScore == -1) {
                    cout << "无效\t";
                } else {
                    cout << students[i].engScore << "\t";
                }
                cout << endl;
                cout << "---------------------------------------" << endl;
                return;
            }
        }
        cout << "学号不存在，请重新输入：" << endl;
        searchStudent();
    }

private:
    vector<Student> students;
};

int main() {
    StudentManager sm;
    sm.createStudents();
    sm.showStudents();
    sm.showStatistics();
    sm.searchStudent();
    return 0;
}

上述代码实现了动态数组的创建，学生信息的录入，成绩列表的输出，成绩统计信息的输出，以及学生信息查询功能。在录入学生信息时，如果输入的学号已经存在，程序会提示重新输入。在录入学生成绩时，如果成绩不在0-100分之间，程序会将该成绩视为无效。在输出成绩列表时，无效成绩会显示为“无效”。在统计成绩信息时，无效成绩不会计入平均分和最高、最低分的计算。在查询学生信息时，如果输入的学号不存在，程序会提示重新输入。